Answer explanation: because the topic is first paved with "air in the balloon", because the swimming ring is also full of air; Buoyancy is formed on the water surface, so the conventional answer is "air". This topic is a brain teaser, which can't be solved by conventional problem-solving ideas. It has something to do with people being covered by swimming rings when they use them, so the answer is that there are people in the swimming rings.

Extended data:

Other types of brain teasers:

1. What animal's ass is more lethal than its mouth? ?

Answer and analysis: wasps (wasps are also called "wasps", "ants" or "wasps". There is a degenerated fallopian tube hidden at the end of the abdomen, which is a poisonous bee needle. In the face of attacks or unfriendly interference, people will attack them in groups, which can cause allergic reactions and poisoning reactions, and even lead to death in serious cases. )

2. Iron will rust if it is left outside. What about gold?

Answer and analysis: it will be taken away (this is a misleading brain trick with two meanings. The first one is to ask about the chemical reaction of gold on the premise that "iron will rust when left outside"; The second meaning is simply to ask what will happen if iron and gold are left outside. Comparing the value of iron and gold, valuable gold will definitely be taken away, so the answer is "gold will be taken away when it is placed outside". )